Multi-piece golf balls containing a multi-layered core structure are provided. The core structure includes a small, heavy inner core (center) having a relatively high specific gravity, an intermediate core layer, and a surrounding outer core layer. The layers of the core structure may have different hardness gradients. In one preferred embodiment, each core layer has a positive hardness gradient. The center of the core comprises a metal material such as copper, steel, brass, tungsten, titanium, aluminum, and alloys thereof. The intermediate core layer is preferably formed from a thermoset composition such as polybutadiene rubber, and the outer core layer is preferably formed from a thermoplastic composition such as an ethylene acid copolymer. The resulting ball has high resiliency and good spin control.

Multi-layered golf balls having a core, intermediate layer, and cover are provided. The ball includes a non-foamed inner core (center) made of a thermoplastic or thermoset composition such as polybutadiene rubber. An intermediate layer comprising a foamed composition, such as polyurethane foam, is disposed about the inner core. The foamed intermediate layer may have a specific gravity gradient within the layer, wherein the outer surface specific gravity is greater than the midpoint specific gravity. Ball constructions having two intermediate layers, wherein at least one layer is a foamed layer can be made. A cover having at least one layer is disposed about the intermediate layer.

Multi-piece golf balls containing a dual-layered core and dual-layered cover are provided. The core structure includes a small, heavy inner core (center) having a relatively high specific gravity, and a surrounding outer core layer. The core layers may have different hardness gradients. The center of the core comprises a metal material such as copper, steel, brass, tungsten, titanium, aluminum, and combinations and alloys thereof preferably dispersed in a thermoplastic polymeric matrix. The outer core layer is preferably formed from a thermoset composition such as polybutadiene. The multi-layered cores and covers have selective specific gravity relationships between the different layers. This helps provide the ball with good flight distance and spin control. The resulting balls have good resiliency and other playing performance properties.

The present invention generally relates to golf balls having an internal skeletal structure that can be self-supporting. The golf ball preferably contains a spherical hollow inner core that is gas or liquid-filled. The ball further comprises an outer shell skeletal structure having a spherical shape and containing apertures that form hollow compartments. In one version, the skeletal structure supports itself and the space inside and around the skeletal structure is hollow. In another embodiment, the space is solid, for example, it may be foam-filled. In yet another version, the hollow space is filled with liquid. Multi-piece golf balls having outer cores, inner covers, and intermediate layers can be made.

Multi-piece golf balls having a solid core made of a foamed composition and a cover are provided. Preferably, the core is dual-layered having has a foam inner core (center) and surrounding thermoset or thermoplastic outer core layer. Preferably, a polyurethane foam composition containing mineral filler particulate, for example, nanoclay particles, is used to form the foam center. The concentration of clay particulate is preferably in a range of 0.1 to 60% by weight. The surrounding outer core layer may be made from non-foamed or foamed compositions. For example, polybutadiene rubber or highly neutralized olefin acid copolymers may be used in the outer core layer. The core layers have different hardness gradients and specific gravity values.

Golf balls comprising a multi-layer core and a cover are disclosed. The multi-layer core comprises a center, an intermediate core layer, and an outer core layer. At least one layer of the multi-layer core is a high specific gravity layer.

Multi-piece golf balls containing a multi-layered core structure are provided. The core structure includes a small, heavy inner core (center) having a relatively high specific gravity, an intermediate core layer, and a surrounding outer core layer. The layers of the core structure may have different hardness gradients. In one preferred embodiment, each core layer has a positive hardness gradient. The center of the core comprises a metal material such as copper, steel, brass, tungsten, titanium, aluminum, and alloys thereof. The intermediate core layer is preferably formed from a first thermoset composition such as polybutadiene rubber, and the outer core layer is preferably formed from a second thermoset composition. The resulting ball has high resiliency and good spin control.

Golf balls and golf ball components made using three-dimensional (3D) additive manufacturing systems are provided. The golf ball includes at least one three-dimensional piece. Preferably, a continuous liquid interface printing method is used to make the three-dimensional structure. Ultraviolet (UV)-light polymerizable materials are used in the method. The method may be used to make single-piece or multi-piece balls. For example, the ball may include an inner core produced by the liquid interface printing method. An outer core layer may be disposed about the inner core, and a cover comprising inner and outer cover layers may encapsulate the core assembly to form the finished golf ball. The outer core and cover layers may be made using conventional molding technologies or the methods of this invention.

The invention provides a golf ball having a core and a cover of one or more layer encasing the core, wherein the core has a center core and a foamed outer layer that directly, or indirectly through another layer, envelops the center core. The foamed outer layer is made of a rubber composition that includes a base rubber, a co-crosslinking agent and an organic peroxide. The foamed outer layer has an inside portion facing the ball center and an outside portion facing the outside of the ball that are unfoamed regions, and contains a foamed region in an intermediate portion therebetween. A method of manufacturing such a golf ball is also provided.

An object of the present invention is to provide a golf ball having excellent spin performance on approach shots under a wet condition and excellent spin performance on approach shots under a condition that there is grass between the golf ball and the dub face. The present invention provides a golf ball comprising a golf ball body and a paint film composed of at least one layer and formed on a surface of the golf ball body, wherein an outermost layer of the paint film located at the outermost layer of the golf ball contains a base resin and a porous filler, the base resin contains a polyurethane obtained by a reaction between (A) a polyisocyanate composition and (B) a polyol composition containing a urethane polyol as a polyol component, the porous filler contains SiO.sub.2 in an amount of 50 mass % or more as a constituent component, and a loss tangent (tan ) of the outermost layer of the paint film measured with a dynamic viscoelasticity measuring apparatus under following conditions has a peak temperature in a range of from 43 C. to 40 C.